问检查是否至少从具有相同类javascript的输入中选择了一个单选按钮

EN

let selectedAnswer = -1;
  const activeInputs = quizes[count].querySelectorAll('input');
  activeInputs.forEach((input, index) => {
    if(input.checked) selectedAnswer = index;
  });
  if (selectedAnswer === -1) {
    alert('Select answer');
    return;
  }

let savedAns = [];
const nextBtn = document.getElementById('next');
const prevBtn = document.getElementById('prev');
const quizes = document.querySelectorAll('.quiz');
const form = document.querySelector('form');
const inputEl = document.querySelectorAll('input');
const total = quizes.length;

//a variable to increment the classes
let ind = 0;

//get all the input elements for each question, assign a class
quizes.forEach(function(element) {
  ind++;
  let inputs = element.querySelectorAll('input');
  inputs.forEach((input) => {
    input.classList.add(`quiz${ind}`)
  })
})

//keep a track of which question is visible 
let count = 0;

//function to hide all the quizes
const hide = function() {
  quizes.forEach((element) => {
    element.style.display = 'none'
  })
}
//show and hide divs when user presses next
nextBtn.addEventListener('click', function() {
  let selectedAnswer = -1;
  const activeInputs = quizes[count].querySelectorAll('input');
  activeInputs.forEach((input, index) => {
    if(input.checked) selectedAnswer = index;
  });
  if (selectedAnswer === -1) {
    alert('Select answer');
    return;
  }

  if (count < total - 1) {
    inputEl.forEach(function(element) {
      if (element.checked) {
        savedAns[count] = element.value;
        console.log(savedAns)
      }
    })
    count++;
  } else {
    inputEl.forEach(function(element) {
      if (element.checked) {
        savedAns[count] = element.value;
        console.log(savedAns)
      }
    })
    alert('no more questions left')
    return
  }
  hide();
  quizes[count].style.display = 'block'
})

prevBtn.addEventListener('click', function() {
  if (count > 0) {
    count--;
  } else {
    alert('no more previous questions')
    return
  }
  hide();
  quizes[count].style.display = 'block'
})

<div class="content">
  <form>
    <div class="quiz">
      <p>Question 1</p>
      <input type="radio" name="answer" value="1">
      <input type="radio" name="answer" value="2">
      <input type="radio" name="answer" value="3">
    </div>

    <div class="quiz" style="display: none;">
      <p>Question 2</p>
      <input type="radio" name="answer" value="1">
      <input type="radio" name="answer" value="2">
      <input type="radio" name="answer" value="3">
    </div>

    <div class="quiz" style="display: none;">
      <p>Question 3</p>
      <input type="radio" name="answer" value="1">
      <input type="radio" name="answer" value="2">
      <input type="radio" name="answer" value="3">
    </div>

    <div class="quiz" style="display: none;">
      <p>Question 4</p>
      <input type="radio" name="answer" value="1">
      <input type="radio" name="answer" value="2">
      <input type="radio" name="answer" value="3">
    </div>
  </form>
  <button id="prev">Prev</button>
  <button id="next">Next</button>
</div>